The prior art method for assembling wire harnesses is illustrated in FIGS. 5, 6A, 6B, 7A, 7B, and 7C. As particularly shown in FIG. 5, the wire harness has connectors A through E. First, wire group W-1, provided with connectors A, B, and D (FIG. 6A) is temporarily bound together. Wire groove W-2, having connectors C and E (FIG. 6B) is similarly temporarily bound. It should be noted that, in wire group W-1, terminal T1, which is to be attached to connector E of wire group W-2, remains exposed. Similarly, terminal T2 of wire group W-2, intended to be connected to wire group W-1, is also unattached.
After the temporary binding of the two wire groups (see FIG. 7A), wire group W-2 is placed on positioning board B for assembly. Thereafter, as shown in FIG. 7B, wire group W-1 is disposed on wire group W-2. At the same time, terminal T1 is inserted into connector E and terminal T2 is inserted into connector A. When the foregoing has been completed, wire groups W-1 and W-2 are wrapped in tape or the like, thereby completing the wire harness. Thereafter, the finished harness is tested for conductivity and integrity.
For ease in explanation, the foregoing prior art discussion has been limited to a single wire harness formed of only two temporarily bound wire groups. However, in usual practice, the wire harness is formed of dozens of wire groups. In assembling such a harness, the wire groups are placed on the positioning board sequentially and the exposed terminals of each group are connected to the corresponding connectors at that time. Thus, it is very easy to make a mistake and insert one or more terminals into the wrong connectors; this is particularly true when there are many temporarily bound wire groups and hence exposed terminals, the possibility of mis-insertion becoming exponentially greater with the increased number thereof.
Moreover, inserting a large number of exposed terminals increases the amount of work and lowers efficiency. Furthermore, the exposed terminals are vulnerable to deformation even to a point where it is difficult to insert them into their respective connectors. Also, the conductivity test is carried out only after the wire harness has been completed and all terminals have been secured in their connectors, since it is necessary to have the connectors in place in order to carry out the test. In this situation, if a harness is found to be defective, it is necessary for it to be completely taken apart and re-assembled. All of these disadvantages add to the difficulty and cost of production.